This relates generally to imaging systems, and more particularly, to imaging systems with stacked-chip image sensors.
Image sensors are commonly used in imaging systems such as cellular telephones, cameras, and computers to capture images. In a typical arrangement, an image sensor includes an array of image sensor pixels and associated control and processing circuitry for operating the image sensor pixels. In a conventional imaging system, the control and processing circuitry is formed laterally from the image sensor pixels on a silicon semiconductor substrate. Each row of image sensor pixels typically communicates with the control circuitry along a common metal line on the silicon semiconductor substrate. Similarly, each column of image sensor pixels communicates with the control circuitry along a common metal line. Image signals captured using the image sensor pixels are then fed to the processing circuitry for performing analog-to-digital signal conversion and desired digital signal processing operations.
In this type of system, a substantial amount of valuable integrated circuit real estate has to be allocated to the control and processing circuitry. This increases the lateral footprint of the image sensor chip. An increased lateral footprint may be undesirable for compact imaging systems such as cellular telephones and cameras.
It would therefore be desirable to be able to provide improved imaging systems such as imaging systems with stacked-chip image sensors and to provide ways for packaging such types of stacked-chip image sensors.